Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of the first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 2 is a front view of the second image thereof;

FIG. 3 is a front view of the third image thereof;

FIG. 4 is a front view of the fourth image thereof;

FIG. 5 is a front view of the fifth image thereof;

FIG. 6 is a front view of the sixth image thereof; and,

FIG. 7 is a front view of the seventh image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-7. The process or period in which one image transitions to another forms no part of the claimed design.

The broken lines depict a display screen or portion thereof and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 